The effects of different carbon sources on growth, tyrosine kinase activity and gene expression of insulin receptor 1 in GIFT tilapia

A feeding trial was conducted to evaluate the effects of different sugar sources on growth performance, serum biochemistry, immunity, insulin receptor 1 and tyrosine kinase activity of GIFT tilapia. Four hundred and eighty fish with specifications of 31.70±0.68 g were selected and placed in 16 aquariums. The experiment was divided into four treatment with four replicates of thirty fish per tank. After 50 days of feeding, the results were as follows: From the indexes of final average weight, weight gain rate and specific growth rate, the growth performance was sucrose, glucose, starch and dextrin group in turn, and the sucrose group performed best (P<0.05). The activcities of acid phosphotase, alkaline phosphotase, superoxide dismutase and lysozyme in sucrose group were significantly higher than that of the other three groups (P<0.05). The serum glucose level of sucrose group and glucose group is significantly higher than that of dextrin group and starch group (P < 0.05). In terms of liver glycogen level, the content of sucrose group was significantly higher than that of dextrin group and starch group (P < 0.05). In terms of muscle glycogen level, the content of sucrose group was the highest and that of starch group was the lowest. The tyrosine kinase activity of glucose group was the highest and significantly different from dextrin group (P< 0.05). The tyrosine kinase activity in muscle was always higher than that in liver (P < 0.05). The IR-1 mRNA in starch group and dextrin group was significantly higher than that in sucrose group. Different sugar source diets had a significant effect on the expression of IR-1 mRNA in the muscle of tilapia. In conclusion, compared with dextrin and starch, sucrose and glucose can be better utilized by GIFT tilapia and show good growth performance. Key words: GIFT tilapia; Carbohydrates; Growth; Immunity; Insulin Receptor 1; Tyrosine Kinase